1. Field of the Invention
This invention relates to visual display panels made up of a plurality of closely adjacent, rectangular modules used as signs and similar visual displays in sports arenas and similar sites for the display of pictorial and/or alpha- numerical images. More particularly, the invention relates to lighted visual displays utilizing light refracting prism filters or lenses and incorporating a pressurized air cooling system, for indoor or outdoor use.
2. The Prior Art
Existing methods of constructing colored and monochrome electronic message boards include the use of arrays of closely spaced painted, incandescent bulbs or arrays of colored filters backed by unpainted, incandescent bulbs. Both have disadvantages.
Painted bulbs have a high initial cost and continuing high replacement cost. The filter mechanism, being comprised of a coat of colored paint, requires careful control of pigment particle size and quantity along with coat thickness. Such control is very difficult. The result has been that the color uniformity throughout a display varies both in color saturation and visible light intensity, a problem which is multiplied when bulbs from different manufacturing batches or from different manufacturers are combined in a display. Because incandescent bulbs have a frontal shape which is usually circular, but they are assigned to fill a square area or pixel, the area which the bulbs fill is often less than 60% of the total area assigned to them. This lack of "pixel fill" reduces visual definition, continuity and uniformity of the matrix display.
The present technology of color filters has limited its use to non-optical of fresnel prismatic designs. This limited the display distribution to the individual lamp output, or collomated the light into a narrow field of view.
When such color filters without light refracting prisms are used there is a lack of intensity and color saturation balance between all colors, especially the absence of effective blue light. The amount of illumination toward the spectators or observers, who are usually positioned below the maximum intensity of each individual filter's distribution, is limited. The filters or collomators have no way of controlling illumination above the horizontal plane and waste up to 50 percent of their intensity above the viewing plane. There is no choice of producing a wide angle or concentrated beam display.
Existing filters and matte finishes are selective in the wave length of light they redirect and therefore cause color shift when viewed from different angles. The reflected energy from the bulb is concentrated on the inside rear surface of the filters causing this part to overheat and limit present filter systems to use of low energy bulbs. This restriction, coupled with the lack of blue light in the incandescent spectrum, results in poor intensity-chromaticity balance which, in turn, results in poor daylight viewing and inadequate color balance for best color blending.